Encapsulation is a well-known technique in the art for protecting components that are sensitive to the elements or for providing time-released delivery of active ingredients. Certain ingredients are easy to encapsulate using conventional techniques. Others, such as sensitive water-soluble components like Vitamin C or aspartamine, are very difficult to encapsulate so that controlled protection and release is provided.
E.P. 0 443 743 to Kubota discloses a method to encapsulate particulate Vitamin C in fine lipid powders by bringing a particulate core substance containing Vitamin C into contact collidingly with particles of a coating material composed of one or more fine powdery lipids, so as to form a coating layer of agglomerated particles of the coating material surrounding the entire particulate core substance.
U.S. Pat. No. 3,161,602 to Herbig discloses a process for making capsules utilizing a three-phase system: a wax-like wall material, a nucleus material, and a substantially inert oily vehicle. The system is heated so that the waxy material melts to a liquid, and is agitated so that the liquid waxy material deposits on each entity of the nucleus material, thereby forming liquid-walled capsule precursor droplets. The entire solution is then cooled with continued agitation, solidifying the waxy walls and forming self-sustaining capsules. This capsule making process has an undesirably long time span from the formation of liquid droplets to the completely solid capsules, which may cause loss of the active component either via diffusion or exclusion mechanisms into the hot inert oily vehicle. This process needs high mechanical agitation and may produce capsules having an uneven distribution of active ingredient in the capsules. This process also produces capsules having a very broad size distribution.
U.S. Pat. Nos. 4,597,970 and 4,828,857, to Sharma, et. al. describe a method to encapsulate aspartame in hydrogenated palm oil by a spray drying process. The process has disadvantages shared with other air spray processes in that it is difficult to provide a uniform, continuous layer onto the outermost surface of the droplets during the congealing step.
U.S. Pat. No. 3,423,489, to Arens, et.al and U.S. Pat. No. 3,779,942, to Bolles disclose a method of forming capsules by forming concentric biliquid columns having an inner core of liquid to be encapsulated and an outer tube of hardenable liquid encapsulating material. The column is caused to travel in a trajectory path for a time sufficient to allow the column to constrict into individual droplets in which the encapsulating material encloses the encapsulated liquid. The stream is preferably directed to travel through a gaseous phase rather than a liquid medium, Column 2, lines 47-51. This method requires the use of special multiple orifice liquid discharging equipment.
U.S. Pat. No. 3,242,237, to Belak, et. al. discloses a process for forming discrete slow release fertilizer particles. According to this method, solid fertilizer is dispersed in melted wax and dropped into water in the form of droplets. Upon contact with the water, the droplets immediately solidify in particle form, and can be separated from the water.
U.S. Pat. No. 3,389,194 to Somerville discloses a method for mass producing small spherical particles. In this process, concentric rods of a fluid fill material and a separate shell or film material are extruded into a conduit through which a stream of carrier fluid is swept. Because the carrier fluid passes the concentric rods of fluid fill material and shell material at a faster rate of flow than the rate of extrusion, the rods are caused to elongate and break off into individual segments. The shell material hardens by cooling or by chemical reaction or solvent extraction.